1. Field of the invention
The present invention concerns a cartridge of the type comprising a longitudinal tube having a transverse open end, a projectile accommodated in and adapted to slide longitudinally of said tube, means for ejecting the projectile from the tube, via said transverse end, by longitudinal relative sliding movement, a pyrotechnic charge in the projectile and means for securing delayed initiation of said pyrotechnic charge.
2. Description of the prior art
In currently known cartridges of this type the means for initiating the pyrotechnic charge generally consist of an exclusively pyrotechnic type fire tranmission path, initiated immediately the ejection process starts by ejection means themselves of a pyrotechnic nature; there are generally inserted into the fire transmission path mechanical safety devices which interrupt this path until the projectile has completely left the tube and establish continuity of the pyrotechnic system as soon as the projectile has left the tube, in order to avoid initiation of the pyrotechnic charge before total disengagement of the projectile from the tube; also, the fire transmission path generally comprises at least one pyrotechnic delay device designed to delay initiation of the pyrotechnic charge of the projectile relative to ejection for a predetermined time interval considered as sufficient for the projectile to exit the tube by a predetermined distance before initiation of the pyrotechnic charge, in order to preserve the safety of the cartridge launching personnel and equipment.
A known solution of this kind is effective provided that no incident disrupts ejection of the projectile out of the tube, and in particular when the ejector means impart to the projectile on leaving the tube a predetermined speed in relation to which the characteristics of the pyrotechnic delay device are defined.
However, should the speed at which the projectile is ejected out of the tube be accidentally less than this predetermined speed, the projectile is at a distance from the tube less than the predetermined distance at the end of the predetermined time interval after which the pyrotechnic charge is initiated, given that continuity of the fire transmission path is established by the mechanical safety means when the projectile leaves the tube, with the result that the pyrotechnic charge may explode too near the cartridge lauching personnel and equipment.
There are sometimes provided in the mechanical safety devices timing means preventing the establishment of continuity of the pyrotechnic system until a certain time interval has elapsed after the projectile leaves the tube, but a precaution of this kind is ineffective given the above hypothesis, according to which the projectile leaves the tube at a speed lower than a predetermined speed according to which the various time-delays are calculated.
An objective of the present invention is to alleviate this disadvantage by proposing means for initiating the pyrotechnic charge of the projectile imposing as a mandatory condition on the possibility of initiating the pyrotechnic charge the requirement for the projectile to leave the tube at a speed considered sufficient for the projectile to be sufficiently far from the tube when the pyrotechnic charge is initiated.